Axial piston pump 20/925353 JCB 3CX/4CX, aftermarket

For the JCB 3CX and 4CX backhoe loaders: axial piston pump 20/925353, an aftermarket part. The card also lists 333/D3951, 333/D5108.

In a variable pump the regulator sets the swashplate angle to match the system's pressure and flow demand; when no function is working, the pump only holds standby pressure. Faults often start in the regulator: a dirty regulator spool stops the pump giving the right flow or holding pressure. Before replacing the pump, measure standby pressure, maximum pressure and the load-sensing signal; if the regulator is at fault, it can be replaced on its own. The case drain line must run straight to tank, since a blocked drain raises case pressure and ruins the shaft seal. Before the first start, fill the pump case with clean oil, or the bearings and pistons will be damaged by running dry. The pump is chosen by part number, and its regulator type, rotation, shaft and flange are compared with the old pump. The pump label carries the Rexroth model code and serial number.

Specifications

Compatibility

Rexroth code: A10VO74DFLR/31R-PSC12N00. The catalogue also has the genuine version of this part. Other parts are in Hydraulic pumps.

Fitting

Before changing a pump or motor, drain and clean the hydraulic tank and renew the suction strainer and filters. Label and remove the hoses and cap the ports. Fit the new unit with the shaft and coupling cleaned and the splines greased as appropriate, renew the flange seals and tighten the bolts evenly to the specified torque. Before the first start, fill the unit case with clean oil; run the engine at idle to bleed the system and then check the pressures with a gauge.